The present invention relates to a gear for twin-screw extruders with a first output shaft, driven by a drive shaft in particular via a reduction gear, and a second output shaft, driven by the first output shaft via two side shafts, arranged on both sides, wherein the shafts are arranged axis parallel and inside a joint gearbox case. There exist various designs for gearbox cases known in the technology. For example, there exists a gearbox case consisting of four gearbox case parts which are attached to each other via horizontal junction planes. The center junction plane extends exactly through the axes of the two drive shafts, while the upper and lower junction planes extend through the axes of the side shafts and parallel to the center junction plane. Owing to the arrangement of the gear train between the two output shafts and the side shafts in the form of a rectangle with the gear shaft axes positioned at its corner points, it is possible to have a continuous adjustment of the spacing between the side-by-side arranged output shafts may be adjusted continuous.
Such gearboxes, which are divided into four parts, result in a drawback, in that when the axial spacing between the two output shafts is changed, the spacing between the two side shafts is changed as well because the length of the gear train remains the same. As a result, the side shafts creep from the associated separating joint, which requires the adaptation and displacement of the separating joints that extend through the axes for the side shafts. This in turn, means that each new axial spacing between the output shafts requires the adaptation of all four gearbox parts that adjoin the side shafts, so that a complete separate gearbox case must be provided even for the slightest difference in the axial spacing.
Based on the foregoing, it is the object of the present invention to provide a gear for twin-screw extruders of the aforementioned type, which gear permits a continuous change in the axial spacing while the gearbox case parts remain unchanged and which is accordingly simplified considerably with respect to the variant variety of these parts.